Method and apparatus for producing a composite nonwoven

ABSTRACT

A method for producing a composite nonwoven in a continuous process sequence, and an apparatus for carrying out the method are provided. A fibrous web is formed by a carding device from a fiber strand, on the surface of which fibrous web subsequently a nonwoven layer of synthetic fibers is laid. To this end, the fibrous web is guided within a suction zone on a laydown belt to a melt-blowing device, in which the synthetic fibers are laid on the surface of the fibrous web by melt-blowing. The fibrous web which is covered with the nonwoven layer is subsequently laid by a nonwoven laying device in a plurality of layers to form the composite nonwoven.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a United States National Phase application ofInternational Application PCT/EP2011/068408 filed Oct. 21, 2011 andclaims the benefit of priority under 35 U.S.C. §119 of German PatentApplication DE 10 2010 049 180.2 filed Oct. 21, 2010, the entirecontents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention pertains to a method for producing a compositenonwoven in a continuous process sequence as well as to a device forcarrying out the method.

BACKGROUND OF THE INVENTION

It is generally known in connection with the production of compositenonwovens that the properties of the composite nonwoven are determinedessentially by the interaction of a plurality of different types ofnonwoven layers. Thus, it was found, for example, in the case ofcomposite nonwovens that are used for soundproofing that it isespecially the differences in the densities of the materials of thenonwoven layers that cause sound waves to be compensated and reflectedto a reduced extent. Such composite nonwovens, which are used forinsulation and soundproofing, have a relatively low area weight, so thatspecial requirements are imposed on their production.

A sound-absorbing thin-layer laminate, which comprises a foam or afibrous web and melt-blown fibers connected thereto, is known from EP 1058 618 B1. The foam or the fibrous web is pulled off in the form of aweb from a first roller, then sprayed with a contact adhesive andpartially dried with an infrared radiator and subsequently broughttogether with a second web of melt-blown fibers. The two webs are thenguided together through pinching rollers and bonded to one another.Another cover layer consisting of a fiber web may optionally be appliedto the thin-layer laminate. This fibrous web cover layer may consist ofmelt-blown spun yarns, which are temporarily bonded by ultrasound. Thethin-layer laminate is subsequently cut into green pieces and fed to amolding press.

It is known from WO 2006/108364 A1 that a single-layer or multilayeredtextile can be produced from polymeric nanofibers, which are obtained byelectrospinning.

EP 0 501 842 B1 and DE 692 09 703 T2 pertain to the production of afabric covering textile for the manufacture of clothing. A firstnonwoven layer consisting of microfibers is produced by melt blowing,while a second, carded nonwoven layer is formed and then arranged underthe first layer. The two layers are knitted and bonded to one another byfluid jets and then dried. The second carded nonwoven layer ispreferably pre-needled. In addition, an adhesive applied in adistributed manner is used to bond the two layers. Furthermore, a thirdnonwoven layer may be added. In one embodiment, a melt-blown microfiberlayer may be applied directly and formed on a second carded layer.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a better productiontechnique for composite nonwovens.

Another object of the present invention is to bring a fibrous webproduced by a carding device to a composite nonwoven at the highest beltspeed possible. Furthermore, one object of the present invention is toform a multilayered soundproofing nonwoven element.

According to the invention, a method is provided for producing acomposite nonwoven in a continuous process sequence in a plurality ofsteps. The steps include feeding of a continuous fiber strand consistingof fibers or fiber blends to a carding device, carding and doffing ofthe fibers to form at least one fibrous web and guiding of the fibrousweb to a holding zone and holding of the fibrous web at a runningconveying means within the holding zone. The method further comprisesmelt blowing of a plurality of synthetic fibers extruded from a polymermelt and laying of the synthetic fibers to form a nonwoven layer on thefibrous web in the area of the holding zone. The fibrous web, withnonwoven layer, is led out of the holding zone to a further processingdevice, especially a nonwoven laying device.

According to another aspect of the invention a soundproofing nonwovenelement having a composite nonwoven is manufactured in accordance withthe described method.

According to another aspect of the invention, a device is provided forproducing a composite nonwoven. The device comprises a carding device, adoffer device, a conveying device and a further processing device,especially a nonwoven laying device. A station for producing a nonwovenlayer, is provided between the doffer device and the further processingdevice. The station comprises a melt-blowing device. A holding device isarranged at the conveying device. The holding device is associated withthe melt-blowing device.

In EP 0501842 B1, a composite nonwoven is produced in a productionprocess from a fibrous web produced by a carding device and a nonwovenlayer produced by melt blowing. In melt blowing, the fibers are producedwith the lowest possible air pressure and the greatest possible distancefrom the fibrous web. However, it is not possible to produce fine fibersin this manner. The prior-art method and prior-art device are thereforesuitable essentially for producing composite nonwovens with relativelyhigh area weights only.

The technique according to the invention has the advantage that evenvery loose and lightweight laid fibrous webs can be combined withcertainty with a nonwoven layer produced by melt blowing. The fibrousweb is prevented from being swirled and altered by the fiber strand ofmelt blowing by the fibrous web being led into a holding zone, e.g., asuction zone, so that the fibrous web becomes fixed, e.g., by thesuction current on the laydown belt. The synthetic fibers producedduring melt blowing are laid directly on the fibrous web in the area ofthe holding or suction zone to form a nonwoven layer and bonded heretoto form a compound. The excess blowing air occurring in the process canlikewise be taken up and removed via a suction zone. To make it possibleto embed the nonwoven layer produced as a cover layer in a structurecomprising a plurality of fibrous webs, the fibrous web with thenonwoven layer may be led out of the suction zone and sent to a nonwovenlaying device. The nonwoven laying device then combines a plurality oflayers of the fibrous web or compound into a composite nonwoven.

To ensure reliable entry of the fibrous web into the laying area of themelt-blowing device and to lead the fibrous web combined with thenonwoven layer out of the laying area, the variant of the presentinvention, in which the fibrous web passes through a plurality ofsuction areas located one after another with separately adjustablesuction capacities within the suction zone, is especially advantageous.Pressure conditions adapted to the particular state of the fibrous webcan thus be generated at the laydown belt in order to minimize a suctioncurrent generated from the environment, on the one hand, and to take upthe blowing air generated by the melt blowing with certainty, on theother hand. In addition, the direct laying of the synthetic fibers canbe affected, moreover, by different pressure settings in order toproduce certain structures within the nonwoven layers.

The fibrous web can be formed, in principle, from fibers and fiberblends consisting of synthetic or natural fibers. However, it was foundto be especially advantageous for binding and bonding if the fibers orfiber blends used to form the fibrous web are formed with a weightpercentage of synthetic fibers in the range of 10% to 100%.

The method variant in which the fibrous material of the synthetic fibersand the polymer melt for extruding the synthetic fibers are formed froman identical basic material is preferably used. The recycling of suchcomposite nonwovens can thus be considerably improved.

The nonwoven layer on the surface of the fibrous web is preferably laidwith fine fibers in order to obtain the properties advantageous forsoundproofing. The method variant in which the synthetic fibers are laidon the fibrous web during melt blowing with a fine fiber cross sectionin the range of 0.2μ to 3μ to form the nonwoven layer is thus preferablyused. However, depending on the application, the composite nonwoven mayalso be produced with coarser synthetic fibers.

The performance capacity of the carding device is exhausted especiallywith the method variant in which the fibrous web is guided continuouslyat a belt speed in the range of 50 m/minute to 200 m/minute afterdoffing until laying. The belt speed is limited essentially by thecapacity of the nonwoven laying device.

To make it possible to produce different types of composite nonwovens,another method variant is proposed, in which a plurality of fibrous websare doffed in parallel next to each other from the carding device andare combined in a sandwich-like pattern after melt blowing and thelaying of the synthetic fibers, with the nonwoven layer forming anintermediate layer between the fibrous webs. Such double fibrous weblayers are especially suitable for protecting the nonwoven layer ofsynthetic fibers obtained as an intermediate layer from furtherprocessing. The structure and distribution of the synthetic fiberswithin the nonwoven layers remain unchanged and can thus be set to thenecessary specific properties already in the production process.

However, it is also possible, in principle, to cover the two fibrouswebs in parallel with a respective nonwoven layer each, which arebrought together into a multilayered nonwoven.

To guarantee cohesion of the fibrous webs laid one on the other in aplurality of layers, it is proposed, furthermore, to feed the compositenonwoven laid by the nonwoven laying device continuously to a bondingdevice and to bond it. Bonding may be carried out here mechanically,chemically or thermally.

In order to obtain the respective nonwoven layers within the compositenonwoven consisting of synthetic fibers as completely as possible, themethod variant is especially advantageous, in which the compositenonwoven is bonded by a heat treatment in a belt type drier, wherein thecomposite nonwoven is led during bonding through a calibration zone, inwhich a calibrating belt adjustable relative to a guide belt acts on thefree top side of the composite nonwoven. Besides bonding, it is alsopossible to set a certain thickness of the composite nonwoven. Themelting of the synthetic fibers within the nonwoven layers can beadvantageously avoided now by the fiber material of the synthetic fibershaving a slightly higher melting point than the synthetic fibers of thefibrous web. This can advantageously also be achieved in the same basicpolymer by means of additives.

For the further processing of such composite nonwovens, provisions are,furthermore, made for the composite nonwoven to be stored in a storagedevice in a roll or, as an alternative, in a stack. In case of stackformation, the storage device additionally has a cutting device in orderto cut the composite nonwoven into individual pieces of nonwoven, whichare then stacked lying one on top of another.

The device according to the present invention is provided for carryingout the method being claimed. This device preferably has a cardingdevice, a doffer device, a conveying device and a further processingdevice, especially a nonwoven laying device, with a station forproducing a nonwoven layer from synthetic fibers being provided betweenthe doffer device and the further processing device or nonwoven layingdevice. To accomplish the object according to the present invention, thestation is designed as a melt-blowing device, with which a holdingdevice, especially suction device, is associated. The suction device ispreferably arranged under a laydown belt of the conveying device, sothat the fibrous web being led on the laydown belt is held on thelaydown belt fixed by means of suction effect.

The suction device for applying suction to the laydown belt is formedaccording to an advantageous variant of the device according to thepresent invention by a plurality of suction chambers, which areconnected to a vacuum source, wherein separate control means areassociated with the suction chambers for setting an individual vacuum.Both the position of the fibrous web and the laying of the syntheticfibers into the nonwoven layer can thus be affected.

To produce the smallest possible amount of waste material during theproduction of the composite nonwoven, the variant of the deviceaccording to the present invention is preferably used, in which themelt-blowing device has a movable spinning head, which can be guidedbetween an operating position above the laydown belt and an inoperativeposition on the side next to the laydown belt. Spinning and themelt-blowing device can thus be started outside the operating position,so that the spinning head being held in the operating position can beused exclusively for producing the composite nonwoven.

To make it possible to produce combinations of fibrous webs, the deviceaccording to the present invention is varied especially such that thedoffer device has two separate doffing sites, which cooperate with twobelt arrangements of the conveying device for receiving and doffing aplurality of fibrous webs. The variant of the device in which one of thebelt arrangements cooperates with the laydown belt and the second beltarrangement is arranged with a conveying section in parallel to thelaydown belt above the spinning head is used to produce a sandwich-likefibrous web combination with a nonwoven layer arranged between them. Thefibrous webs doffed from the calibrating device can thus be guided inone plane without deflection.

However, it is also possible as an alternative for the second beltarrangement to have a second laydown belt and for a second spinning headof the melt-blowing device to be associated with the second laydownbelt. A plurality of fibrous webs with a combined nonwoven layer canthus be produced.

The further processing of the composite nonwoven takes place within thedevice by a conveyor belt device, which connects the nonwoven layingdevice to a bonding device and to a storage device. The compositenonwoven can thus be stored in the form of a roll or stack within thestorage device.

For bonding, it is proposed that the device have a belt type drier witha guide belt and with a calibrating belt arranged above the guide belt,wherein the calibrating belt is designed such that it is adjustable inheight relative to the guide belt. Specific material thicknesses of thecomposite nonwoven can thus also be produced besides bonding.

The method according to the present invention will be explained in moredetail below on the basis of some exemplary embodiments of the deviceaccording to the present invention for producing a composite nonwovenwith reference to the figures attached. The various features of noveltywhich characterize the invention are pointed out with particularity inthe claims annexed to and forming a part of this disclosure. For abetter understanding of the invention, its operating advantages andspecific objects attained by its uses, reference is made to theaccompanying drawings and descriptive matter in which preferredembodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic first partial view of a first exemplary embodimentof a device according to the present invention;

FIG. 2 is a schematic second partial view of the exemplary embodimentfrom FIG. 1;

FIG. 3.1 is a schematic cross-sectional view of the melt-blowing deviceof the exemplary embodiment from FIG. 1 in one of a plurality ofoperating positions;

FIG. 3.2 is a schematic cross-sectional view of the melt-blowing deviceof the exemplary embodiment from FIG. 1 in another of a plurality ofoperating positions;

FIG. 4 schematic partial view of another exemplary embodiment of thedevice according to the present invention; and

FIG. 5 is a schematic partial view of another exemplary embodiment ofthe device according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in particular, the present invention pertainsto a method and a device for producing a composite nonwoven (36) and asound-absorbing nonwoven element produced therefrom.

FIGS. 1 and 2 show a first exemplary embodiment of the device accordingto the present invention for carrying out the method according to thepresent invention. FIG. 1 shows a partial view of the front half of themachine and FIG. 2 shows a partial view of the rear half of the machine.

The device according to the present invention has a carding device (1)in the front half of the machine according to FIG. 1. The carding device(1) cooperates with a feeding device (2) at one end and with a dofferdevice (7) at the opposite end. A breast roller (4) and a main cylinder(5), on the circumference of which a plurality of carding elements (6)act, are arranged between the feeding device (2) and doffer device (7).A plurality of feeding systems (3) are provided between the feedingdevice (2) and breast roller (4) in order to take up a fiber strand madecontinuously available by the feeding device (2) and to move same to thebreast roller (4). The fibers are carded at the breast roller (4) andmain cylinder (5) and doffed as a fibrous web via the doffer device (7)associated in the main cylinder (5).

It shall be expressly mentioned here that the design and number ofcylinders and carding elements used in the carding device are indicatedas examples only. It is also possible, in principle, to use cardingdevices with only one cylinder.

The doffer device (7) is formed in this exemplary embodiment by adoffing cylinder system (8), which directly cooperates with a conveyorbelt (10.1) of a conveying device (9). The conveying device (9) isformed in this exemplary embodiment by a first conveyor belt (10.1), alaydown belt (11) and a second conveyor belt (10.2), which cooperatetogether to take up and doff a fibrous web (32) continuously from thecarding device (1).

A melt-blowing device (12) is associated with the laydown belt (11) on atop side and a holding device (17) is associated with it on anunderside. A nonwoven layer (35) consisting of melt-blown syntheticfibers (33) is applied, e.g., with a stream of compressed gas, to thesurface of the fibrous web (32) with the melt-blowing device (12). Thecomposite of fibrous web (32) and nonwoven layer (35) will hereinafterbe called compound.

The holding device (17) can act on the fibrous web (32) and/or on astream of compressed gas of the melt-blowing device (12). It can hold,e.g., the fibrous web (32) on the laydown belt (11) and stabilize sameagainst the incident stream of compressed gas with the melt-blown fibers(33). It can also act guidingly on the stream of compressed gas and thefiber strand. It can, e.g., draw off the compressed gas stream in acontrolled manner after the release of the fibers (33) to the fibrousweb (32). The holding device (17) may also be designed, e.g., as asuction device.

The laydown belt (11) is designed as a gas-permeable belt and is ledover a total of three suction chambers (18.1, 18.2, 18.3) of the suctiondevice (17). The suction chambers (18.1, 18.2 and 18.3) of the suctiondevice (17) are connected to a vacuum source (not shown here) viaseparate suction lines (19.1, 19.2 and 19.3) independently from eachother and their suction capacity can be set independently from eachother by means of associated control means (20.1, 20.2, 20.3).

Above the middle suction chamber (18.2), the melt-blowing device (12)has a spinning head (13), which is coupled by a melt line (34) with anextruder (14). The spinning head (13) also has a port to a compressedgas supply unit (15), e.g., a compressed air supply unit, which isconnected to a compressed air source (not shown here) via a controlvalve (16). On its underside, the spinning head (13) has a melt blowingnozzle, which extends essentially over the entire width of the laydownbelt (11). The width of the melt blowing nozzle of the spinning head(13) is identical to the working width of the carding device (1). Theworking widths of the carding device (1) can thus be designed in therange of 2 m to 4 m and more. The width of the melt blowing nozzle iscorrespondingly likewise in the range of 2 m to 4 m.

The spinning head (13) as well as the extruder (14) are held in thisexemplary embodiment at a movable carrier (21), by which the spinninghead (13) can be moved back and forth between an operating position andan inoperative position. A cross section of the melt-blowing device (12)is shown for illustration in the operating position in FIG. 3.1 and inthe inoperative position in FIG. 3.2. Reference is therefore made hereadditionally to FIGS. 3.1 and 3.2.

In the operating position, the spinning head (13) of the melt-blowingdevice (12) is located directly above the laydown belt (11), to whichsuction is applied on its underside by the suction chamber (18.2). Thesuction chamber (18.2) is connected to a vacuum source, not shown here,via a suction line (19.2) and a control means (20.2).

The carrier (21) of the spinning head (13) and of extruder (14) isdesigned as a movable carrier and can be displaced to and fro, forexample, via a rail system or a roller system at right angles to thelaydown belt (11). The ports on the spinning head (13) remain unchanged.Thus, the spinning head (13) is connected to the extruder (14) via themelt line (34). Connection to a pressure source is provided via thecompressed air supply unit (15) and control valve (16).

As is shown in FIG. 3.2, carrier (21) can be displaced such that thespinning head (13) is maintained in an inoperative position on the sidenext to the laydown belt (11). Maintenance operations and, when startingthe process, spinning start operations can be performed in this positionwithout a fibrous web (32) being led at the laydown belt (11).

As is shown in the view in FIG. 1, a nonwoven laying device (22) isarranged next to the melt-blowing device (12), and the conveyor belt(10.2) of the conveying device (9) is held between the melt-blowingdevice (12) and nonwoven laying device (22). The nonwoven laying device(22) has laying means, not shown here in more detail, for laying thefibrous web (32) or compound being fed by means of the conveyor belt(10.2) in a steady and, e.g., uniform to and fro motion on a conveyorbelt of a conveyor belt device (23) in a plurality of layers and with aselectable number of layers and for forming a composite nonwoven (36).The area weight of the multilayered composite nonwoven (36) may bepossibly controlled and regulated here as needed and changed globally orlocally in the transverse and/or longitudinal direction (so-calledprofiling).

The conveyor belt is operated correspondingly depending on the number oflayers and the laying width with a low belt speed. The conveyingdirection of the conveyor belt device (23) is thus directed at rightangles to the conveying direction of the conveying device (9). Thefollowing units of the device according to the present invention whichare arranged downstream form a second longitudinal side of the machine,on which the devices are arranged one after another for the furtherprocessing of a composite nonwoven.

Thus, it is shown in FIG. 2 that the nonwoven laying device (22) isfollowed over the further course by a bonding device (24) and a storagedevice (28). The bonding device (24) is formed in this exemplaryembodiment by a belt type drier (25), which has a guide belt (26) and acalibrating belt (27) arranged above the guide belt in a calibrationzone. The calibrating belt (27) is designed as a belt that is adjustablein height in relation to the position of the guide belt (26), so that acomposite nonwoven (36) being guided on the guide belt (26) can bebonded with a defined material thickness. Bonding is carried out here bymeans of heat treatment and is called thermobonding by persons skilledin the art. Stable cohesion of all fibers is generated here by partiallymelting the fiber material of some fibers within the composite nonwoven.

The multilayered composite nonwoven (36) laid by the nonwoven layingdevice (22) is fed to this end continuously to the bonding device (24)by the conveyor belt device (23).

The storage device (28), which is formed by a winding station (29) inthis exemplary embodiment, is provided on the outlet side of bondingdevice (24). The winding station (29) produces a roll of nonwovenmaterial (30) from the composite nonwoven (36) being fed continuously.

The device according to the present invention, shown in FIGS. 1 and 2,is especially suitable for carrying out the method for producing acomposite nonwoven (36) that is used as an insulating material. Suchcomposite nonwovens usually have a relatively low area weight and arelatively loose structure of the fibers contained within the compositenonwoven.

As is shown in FIG. 1 and FIG. 2, a continuous fiber strand of fibers orfiber blends is charged at first in the method to the carding device(1). The fibers (31) are fed via the feeding device (1) and carded bymeans of one or more cylinder systems and doffed as a fibrous web (32).The fibrous web (32) is taken up by means of the conveying device (9)and doffed continuously. The conveyor belts (10.1) and (10.2) of theconveying device (9) are operated in this process at a belt speed in therange of 50 m/minute to 200 m/minute. The belt speed is determined bythe carding device (1) or the nonwoven laying device (22).

The fibrous web (32) is transferred in the further course from the firstconveyor belt (10.1) to the laydown belt (11), which delivers thefibrous web (32) to the melt-blowing device (12), in which a nonwovenlayer (35) of synthetic fibers (33) is laid on the surface of thefibrous web (32) and the compound is formed. To take up and produce thenonwoven layer (35) on the surface of fibrous web (32), the fibrous web(32) is guided on the laydown belt (11) through a holding zone, e.g., asuction zone. The suction zone is formed by the three suction chambers(18.1, 18.2 and 18.3) in this exemplary embodiment. Suction is appliedin the suction zone to the underside of the laydown belt (11), which isdesigned as a gas-permeable belt and may be, for example, a screen beltor fabric belt. As a result, a holding force is generated at the fibrousweb (32), so that the structure of the fibrous web (32) is preserved inthe laying zone of the synthetic fibers (33) despite the air streamsgenerated during melt blowing.

A polymer melt is melted during melt blowing by means of an extruder(14) and fed to a spinning head (13). A melt blowing nozzle is providedon the underside of the spinning head (13), and a plurality of syntheticfibers (33) are extruded through said melt blowing head and pulled offby means of compressed gas, e.g., compressed air, which is likewise fedin the spinning head (13), and blown in the direction of the laydownbelt (11). The melt blowing nozzle, melt throughput as well as settingof the compressed air are preferably selected here to be such thatrelatively fine synthetic fibers (33) are produced. The synthetic fibers(33) preferably have a fine fiber cross section in the range of 0.5μ to3μ in order to form the nonwoven layer (35) on the surface of thefibrous web (32).

The synthetic fibers (33) are preferably laid on the fibrous web (32) inthe middle area of the suction zone, so that different settings of thesuction capacity are possible in an inlet area, in a contact area and inan outlet area of the fibrous web (32) due to the separately adjustablesuction capacities of the suction chambers (18.1 through 18.3). On theone hand, a sufficient holding force can be generated on the fibrous web(32) during the entry of the fibrous web (32). On the other hand, thelaying of the synthetic fibers (33) can be affected by means ofdifferent suction capacities. Besides, the blowing air produced duringmelt blowing can also be integrated by the ambient air of the suctionchambers into the synthetic fiber laying process. Additional effects andstructures can thus be produced in the nonwoven layer.

After the nonwoven layer (35) has been laid on the surface of thefibrous web (32), the fibrous web (32) of the nonwoven layer (35), i.e.,the compound, is fed by the conveyor belt (10.2) to the nonwoven layingdevice (22). The fibrous web (32) with the nonwoven layer (35) is laidby the nonwoven laying device (22) in a plurality of layers to form thedesired composite nonwoven (36). The composite nonwoven (36) has, e.g.,at least two layers of fibrous web (32) laid one over the other or aplurality of double layers of fibrous web (32) or compound. Thecomposite nonwoven (36) is doffed continuously by the conveyor beltdevice (23) and fed to the bonding device (24). The belt speed of theconveyor belt device (23) depends on the number of layers and the layingwidth of the nonwoven laying device (22).

The composite nonwoven (36) is thermally bonded within the bondingdevice (24), where the material thickness of the composite nonwoven (36)is determined especially in a calibration zone by the interaction of theguide belt (26) and calibrating belt (27).

The composite nonwoven (36) is wound up into the nonwoven roll (30)after bonding.

Preferably 100% synthetic fibers are used to form the fibrous web (32)in the method and device shown in FIGS. 1 and 2. The fiber material ofthe synthetic fibers and the polymer melt for extruding the syntheticfibers (33) are preferably formed from an identical basic material here.For example, a polyester or a polypropylene would be a suitable basicmaterial. The specific properties of the fiber material of the syntheticfibers and of the material of the polymer melt are coordinated here withone another such that essentially only the synthetic fibers in thefibrous web are melted for bonding during thermobonding. The fibermaterial of the synthetic fibers, which may also be formed frombiofibers, is thus provided with a somewhat lower melting point than thepolymer melt.

However, the exemplary embodiment according to FIG. 1 and FIG. 2 couldalso be expanded such that a second carding device with a doffer deviceis arranged between the melt-blowing device (12) and nonwoven layingdevice (22) in order to produce a second fibrous web. The second fibrousweb would be laid on the nonwoven layer, so that the nonwoven layer isheld in a sandwich-like manner between lower and upper fibrous weblayers.

It is possible, in principle, to form one of the fibrous webs or bothfibrous webs from a fiber blend consisting of synthetic fibers andnatural fibers. To obtain sufficient strength during thermobonding, atleast 10% of the fibers are formed by synthetic fibers.

A single-layer fibrous web (32) is doffed from the carding device (1)for producing the composite nonwoven (36) in the exemplary embodimentshown in FIGS. 1 and 2. However, it is also possible, in principle, toprovide the doffer device (7) with a plurality of doffer sites. Thus, apartial view of another exemplary embodiment of the device according tothe present invention for carrying out the method according to thepresent invention is shown schematically in FIG. 4. The exemplaryembodiment is essentially identical to the above-mentioned exemplaryembodiment according to FIGS. 1 and 2, so that only the differences willbe explained here and reference will otherwise be made to theabove-mentioned description.

In the exemplary embodiment shown in FIG. 4, the doffer device (7) formstwo doffer sites (37.1) and (37.2). A doffing roller system (8) each isprovided in each of the doffing sites (37.1) and (37.2) in order to takeup a fibrous web (32.1) and (32.2) each and feed it to the conveyingdevice (9). Conveying device (9) has a lower belt arrangement (38.1) andan upper belt arrangement (38.2) in this exemplary embodiment. The beltarrangement (38.1) has a design identical to that in the exemplaryembodiment according to FIGS. 1 and 2. The upper belt arrangement (38.2)has a conveying section (10.3), which is led in parallel to the laydownbelt (11) above spinning head (13). The upper belt arrangement (38.2)may be of a multipart design here in the form of a plurality of conveyorbelts or also of a one-part design formed by an endlessly runningconveyor belt.

The two belt arrangements (38.1) and (38.2) of the conveying device (9)are brought together in the area between the melt-blowing device (12)and nonwoven laying device (22) such that the two fibrous webs (32.1)and (32.2) are put together in a sandwich-like manner and enclose thenonwoven layer (35) between them. The multilayered nonwoven ormultilayered compound thus formed is then fed to the nonwoven layingdevice (22) and laid in a plurality of layers to form the compositenonwoven (36).

The suction zone is formed by one suction chamber (18) of the suctiondevice (17) only in this exemplary embodiment when the nonwoven layer(35) is formed by the melt-blowing device (12). The suction chamber (18)preferably extends here in the longitudinal direction of the laydownbelt (11) such that a holding force is produced at the fibrous web (32)by the suction effect of the suction chamber (18) immediately before orduring the entry of the fibrous web (32) into the laying zone of themelt-blowing device (12).

A multilayered fibrous web (32.1, 32.2) with a nonwoven layer (35)located inside can thus be produced with the exemplary embodiment shownin FIG. 4.

However, it is also possible, in principle, that both fibrous webs(32.1) and (32.2) are covered with a nonwoven layer (35.1, 35.2)consisting of synthetic fibers. Thus, a partial view of anotherexemplary embodiment, which is essentially identical to the exemplaryembodiment in FIG. 4, is shown schematically in FIG. 5. Unlike in theabove-mentioned exemplary embodiment according to FIG. 4, the beltarrangements (38.1) and (38.2) have an identical design, so that thebelt arrangement (38.1) has a lower laydown belt (11.1) and the beltarrangement (38.1) has an upper laydown belt (11.2). A suction chamber(18.1) and (18.2) each, which apply suction to the respective laydownbelts (11.1) and (11.2) independently from one another, is associatedwith each of the laydown belts (11.1) and (11.2). A spinning head (13.1)and (13.2) each of the melt-blowing device (12) is arranged above thelaydown belts (11.1) and (11.2). The spinning heads (13.1) and (13.2)are coupled together with an extruder (14).

Unlike in the exemplary embodiment according to FIG. 4, one nonwovenlayer (35.1) and (35.2) each is produced at each of the fibrous webs(32.1) and (32.2) in the exemplary embodiment according to FIG. 5. Thestructures and designs of the nonwoven layers (35.1) and (35.2) may beidentical or different.

The two fibrous webs (32.1) and (32.2) are subsequently brought togetherwith the nonwoven layers (35.1) and (35.2) laid on the surfaces and fedas a multilayered nonwoven or multilayered compound to the nonwovenlaying device (22). The method being shown and the device being showncan thus be expanded in a flexible manner in order to producesingle-layer or multilayered fibrous webs for producing compositenonwovens.

For example, three fibrous webs, which are put together by means ofthree conveyor belt systems to form a multilayered nonwoven ormultilayered compound and fed to a nonwoven laying device, could beproduced simultaneously in an advantageous variant of the presentinvention by means of a carding device by three separate doffer sites.Two melt-blowing devices, which are associated with the conveyor beltsystem, could be arranged between the carding device and the nonwovenlaying device, so that two of the three fibrous webs are covered with anonwoven layer made of synthetic fibers prior to bringing together.Multilayered nonwovens, which contain synthetic fibers from twodifferent polymers, can be produced with this variant of the presentinvention.

As an alternative, the melt-blowing devices could also be associated oneafter another with a conveyor belt system in order to lay two nonwovenlayers on a fibrous web.

The devices for producing the composite nonwoven, which are shownespecially in FIGS. 1 and 2, are examples. The method according to thepresent invention and the device according to the present invention are,in principle, also suitable for producing composite nonwovens in whichbonding is brought about by chemical agents or by mechanical means, forexample, needling. In addition, the composite nonwoven may also be cutinto individual pieces of nonwoven for storage and then stacked up intoa stack. The winding station could thus be replaced with a stackingstation.

Various further variants of the embodiments shown and described aboveare possible. The holding device (17) may have a different design and bearranged differently, e.g., as an electrostatic or mechanical holdingdevice, which holds the fibrous web (32) with electrostatic forces,hooks or needles or the like on the laydown belt (11, 11.1, 11.2) andstabilizes it against being blown away. The laydown belt (11, 11.1,11.2) may again be permeable to gas. A suction device can be eliminatedin these cases. A suction device may be present as an alternative, butit may be designed for a lower capacity. Furthermore, it is possible toarrange a suction device elsewhere. In the exemplary embodiments beingshown, it sucks from the laydown belt (11, 11.1, 11.2) and acts on theunderside of the carrying run located there. As an alternative, it maybe arranged elsewhere and outside the laydown belt.

Other conveying means may be used for the fibrous web (32) instead ofthe conveyor belts described.

In the exemplary embodiments shown and described, the further processing(device) (22) is a nonwoven laying device (22), e.g., designed as acrosslapper, especially as a belt type laying device, which lays thesingle-layer or multilayered compound fed on the laydown belt (23) in azigzag and scale-like layer pattern. As an alternative, a nonwovenlaying device (22) may also be designed as a carriage type layingdevice, camelback laying device or the like. In another variation, thesingle-layer or multilayered compound may be cut and divided into piecesbefore laying, and the pieces are laid one on top of anotherindividually and optionally flush one on top of another to form amultilayered composite nonwoven (36). The nonwoven laying device (22) isdesigned in a correspondingly modified manner for this.

In the preferred exemplary embodiments shown, the single-layer ormultilayered compound is fed to a nonwoven laying device (22)immediately after it has been formed. In a variation of this, anintermediate step may be inserted between the formation of the compoundand a nonwoven laying device (22). For example, the single-layer ormultilayered compound may be taken up and stored temporarily, and it isfed to a nonwoven laying device (22) or to another further processingprocess only later. Said compound may, e.g., be stabilized in a suitablemanner and wound up in an intermediate step.

The further processing may be designed in another manner. For example, amultilayered design of the composite nonwoven (36) may be eliminated bythe single-layer or multilayered compound being fed directly to anotherfurther processing, e.g., bonding, especially needling, thermobonding orthe like and possibly fed to a storage unit.

Mat-like, shell-like soundproofing parts or sound-absorbing nonwovenelements or soundproofing parts or sound-absorbing parts of other formscan be manufactured from the single-layer or multilayered compositenonwoven (36). A shaping process with pressing and possibly heating maypossibly be used for this. A multilayered composite nonwoven (36) with anonwoven layer (35, 35.1, 35.2) located on the outside and/or on theinside has special advantages for soundproofing. The exemplaryembodiments shown for a multilayered or sandwich type composite nonwoven(36) are especially advantageous for this. A composite nonwoven may alsobe produced with a single-layer design in the above-mentioned manner andused for insulation purposes.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the principles ofthe invention, it will be understood that the invention may be embodiedotherwise without departing from such principles.

1. A method for producing a composite nonwoven in a continuous processsequence the method comprising the steps of: feeding a continuous fiberstrand formed of fibers or fiber blends to a carding device; carding anddoffing of the fibers to form at least one fibrous web; guiding of thefibrous web to a holding zone and holding the fibrous web at a runningconveying means within the holding zone; melt blowing a plurality ofsynthetic fibers extruded from a polymer melt and laying of thesynthetic fibers to form a nonwoven layer on the fibrous web in the areaof the holding zone; leading the fibrous web with nonwoven layer out ofthe holding zone to a further processing device.
 2. A method inaccordance with claim 1, wherein the fibrous web is sucked onto theconveying means in a holding zone designed as a suction zone.
 3. Amethod in accordance with claim 1, wherein the fibrous web passesthrough a plurality of suction areas located one after another withseparately adjustable suction capacities within a suction zone.
 4. Amethod in accordance with claim 1, wherein the fibrous web with nonwovenlayer is laid in a nonwoven laying device in a plurality of layers toform a composite nonwoven.
 5. A method in accordance with claim 1,wherein the fibers or fiber blends for forming the fibrous web areformed from synthetic fibers at a weight percentage in the range of 10%to 100%.
 6. A method in accordance with claim 1, wherein the fibermaterial of the synthetic fibers and the polymer melt for extruding thesynthetic fibers are formed from an identical basic material.
 7. Amethod in accordance with claim 1, wherein the synthetic fibers are laidon the fibrous web with a fine fiber cross section in the range of 0.2μto 3μ to form the nonwoven layer during melt blowing.
 8. A method inaccordance with claim 1, wherein the fibrous web is led continuously ata belt speed in the range of 50 m/minute to 200 m/minute after doffinguntil laying.
 9. A method in accordance with claim 1, wherein aplurality of fibrous webs are doffed from the carding device one on topof another and put together in a sandwich pattern after melt blowing andlaying of the synthetic fibers, the nonwoven layer forming anintermediate layer between the fibrous webs.
 10. A method in accordancewith claim 1, wherein a plurality of fibrous webs are covered with anonwoven layer each and the fibrous webs are brought together with thenonwoven layers before the further processing device comprising anonwoven laying device, to form a multilayered nonwoven.
 11. A method inaccordance with claim 1, wherein a composite nonwoven laid by a nonwovenlaying device is fed continuously to a bonding device and bonded.
 12. Amethod in accordance with claim 1, wherein a composite nonwoven isbonded by heat treatment in a belt type drier, wherein the compositenonwoven is passed, during bonding, through a calibration zone, in whicha calibrating belt, that is adjustable relative to a guide belt, acts ona free surface of the composite nonwoven.
 13. A method in accordancewith claim 1, wherein a composite nonwoven is fed to a storage deviceand stored as a roll or as a stack.
 14. A device for producing acomposite nonwoven, the device comprising: a carding device; a dofferdevice; a conveying device; a further processing device a station, forproducing a nonwoven layer, provided between the doffer device and thefurther processing device, wherein the station comprises a melt-blowingdevice; and a holding device arranged at the conveying device, theholding device being associated with the melt-blowing device.
 15. Adevice in accordance with claim 14, wherein the holding device comprisesa suction device.
 16. A device in accordance with claim 15, wherein thesuction device is arranged under a laydown belt, of the conveyingdevice.
 17. A device in accordance with claim 16, wherein the suctiondevice has a plurality of suction chambers for applying suction to thelaydown belt and further comprising a separate control means associatedwith the suction chambers for setting a vacuum.
 18. A device inaccordance with claim 16, wherein the melt-blowing device has a movablespinning head, which can be guided between an operating position abovethe laydown belt, and an inoperative position on a side next to thelaydown belt.
 19. A device in accordance with claim 14, wherein thedoffer device has two separate doffing sites, which cooperate with twobelt arrangements of the conveying device for picking up and doffing aplurality of fibrous webs.
 20. A device in accordance with claim 19,wherein: the conveying device comprises a laydown belt; and one of thebelt arrangements cooperates with the laydown belt and that a secondbelt arrangement is arranged with a conveying section above the spinninghead in parallel to the laydown belt.
 21. A device in accordance withclaim 20, wherein the second belt arrangement has a second laydown beltand that a second spinning head of the melt-blowing device is associatedwith the second laydown belt.
 22. A device in accordance with claim 14,wherein the further processing device comprises a nonwoven laying devicethat cooperates with a conveyor belt device, a bonding device and astorage device, wherein the composite nonwoven laid by the nonwovenlaying device is led to a roll or a stack in a storage station.
 23. Adevice in accordance with claim 22, wherein the bonding device has abelt type drier with a guide belt and with a calibrating belt arrangedabove the guide belt and that the calibrating belt is designed as aheight-adjustable belt relative to the guide belt.
 24. A soundproofingnonwoven element, wherein the nonwoven element has a composite nonwovenand is manufactured by a method comprising the steps of: feeding acontinuous fiber strand formed of fibers or fiber blends to a cardingdevice; carding and doffing of the fibers to form at least one fibrousweb; guiding of the fibrous web to a holding zone and holding thefibrous web at a running conveying means within the holding zone; meltblowing a plurality of synthetic fibers extruded from a polymer melt andlaying of the synthetic fibers to form a nonwoven layer on the fibrousweb in the area of the holding zone; leading the fibrous web withnonwoven layer out of the holding zone to a further processing device.